How to Get Wither Roses in Minecraft

Guide Java Bedrock

Quick answer: Wither roses drop when any mob or player is killed by the wither - one rose per kill. Summon the wither in a mob-filled pit (or use a wither rose farm design) and every creature it kills leaves a rose that inflicts the Wither effect on touch.

What you need

4 soul sand + 3 wither skeleton skulls (a wither)
Disposable mobs (eggs, pens or spawners)
Obsidian or bedrock trap for farming
Armor and milk for safety

Step by step

Understand the source: wither roses can't be crafted, grown or bonemealed. They only appear when the wither kills something - any mob or player drops exactly 1 wither rose on death.
Set up a rose run: summon the wither in a closed pit full of cheap mobs (chickens, cows, sheep from eggs or pens). Every kill plants or drops a rose.
Know the placement rules: the rose is placed on the block where the victim died if a flower can survive there (dirt, grass, netherrack, soul sand, soul soil in Java...); otherwise it drops as an item. With mob_griefing=false it always drops as an item.
Farm seriously: wither rose farm designs trap the wither in bedrock (End exit portal) or obsidian and feed it mobs from spawners or breeders, producing thousands of roses per hour.
Handle with care: touching a wither rose inflicts the Wither effect - 1 heart of damage every half second, lingering 1 second after you step off. Wither skeletons, the wither and the ender dragon are immune; in Peaceful the roses do nothing.
Use them in mob farms: a floor of wither roses is the classic kill mechanism for wither skeleton farms and other Nether farms - roses damage only non-immune mobs, no player input needed.
Other uses: craft black dye, brew wither-effect suspicious stew, and even breed bees with them (the flower hurts the bee, but it works). A potted wither rose is harmless decoration.
Odd detail: in Java, endermen can pick up wither roses and drop them when killed - a rare accidental source.

Java vs Bedrock

The drop mechanic is identical in both editions. Java extras: roses can be planted on soul soil, endermen can carry them, and mob_griefing=false forces item drops. In Bedrock, a snowlogged wither rose emits no particles and deals no damage.

Versions: Wither roses were added in Java Edition 1.14 (Village & Pillage) and Bedrock 1.13.0. Bee breeding with wither roses arrived in Bedrock 1.14.0.

Frequently asked questions

How do you get wither roses?

They only drop when the wither kills a mob or player - one rose per kill. Summon the wither near disposable mobs and collect the roses it leaves behind.

Can you grow or craft wither roses?

No. They can't be crafted and bone meal doesn't duplicate them (unlike normal flowers in Bedrock). The only source is wither kills - which is why wither rose farms exist.

Do wither roses hurt you?

Yes: standing on one inflicts the Wither effect, 1 heart every half second. Wither skeletons, the wither and the ender dragon are immune. In a flower pot, or snowlogged in Bedrock, they're harmless.

What are wither roses used for?

Kill floors in mob farms (especially wither skeleton farms, since skeletons are immune), black dye, wither-effect suspicious stew, and dark decoration.